Noise absorption of gap graded mixtures with rubberized asphalt

Sound absorption is a material property which contributes to reduce noise levels when sound propagates from the source to the receiver. Porous materials have particularly good absorption characteristics, not only because of the high percentage of air voids, but also due to their flow resistance and tortuosity. Road surface layers made of gap graded mixtures are among those absorptive materials. Because these mixtures have a void content that may be considered of medium level, this study aims to characterise their absorption capacity, particularly of those with rubberized asphalt binder. For this purpose, absorption measurements in a Kundt’s tube were performed on cores extracted from slabs with different gap graded asphalt. In order to study the effect of the rubberized asphalt, the mixtures were produced in laboratory with two types of rubberized asphalt and with unmodified asphalt. The effect of the binder was pondered with this procedure. Furthermore, the effect of porosity was considered bycomparing the results of mixtures which have considerably high and low void contents.(undefined

First detection of Bursaphelenchus luxuriosae associated with Pinus pinaster in Portugal

During a field survey carried out on symptomatic maritime pine trees (Pinus pinaster) in Góis, central Portugal, Bursaphelenchus luxuriosae was isolated for the first time in Portugal, and in Europe. Identification of the nematodes was based on morphological characters and molecular analyses for this species. The general morphology of both females and males is in agreement with the original description for B. luxuriosae, namely the typical morphology of the male spicules and the conspicuous morphology of female tail. Species identification was confirmed through sequencing of the ITS rDNA region and the fragment spanning the D2/D3 domain of the 28S rDNA gene. This species belongs to the xylophilus-group and is the third species in this group known in Portugal. The nematodes were retrieved in small numbers (<100 nematodes/100 g dry wood), and no insect vector association could be established

Avaliação do desempenho acústico de dispositivos de redução do ruído de tráfego

O desenvolvimento urbano que se verificou em Portugal nas últimas décadas do século 20 foi acompanhado por um rápido e elevado crescimento do tráfego e, consequentemente, pela construção de vias rodoviárias quer urbanas quer rurais. A partir do ano 1980, as políticas de controlo do ruído levaram as administrações rodoviárias e os construtores a aplicarem medidas de mitigação do ruído que passaram sobretudo pela construção de barreiras acústicas e, em menor grau, pela aplicação de pavimentos com características que produzem menos ruído. Em ambos os casos, a avaliação do desempenho acústico permite a comparação das especificações de projecto com dados de desempenho reais e a verificação do mesmo a longo prazo para a devida validação das soluções adoptadas. Neste trabalho apresentam-se os métodos essenciais para uma gestão eficaz do ruído rodoviário, que permitem avaliar o ruído de contato pneu-pavimento e o desempenho acústico de dispositivos de redução de ruído do tipo barreiras acústicas. Apresenta-se ainda um método complementar para a determinação da absorção sonora em pavimentos rodoviários.The urban development that has occurred in Portugal in the last decades of the 20th century was accompanied by a fast growth of road traffic and, consequently, by the construction of rural and urban roadways. After 1980, the noise control policies lead the road administrations and constructors to apply noise mitigation measures, like barriers but also pavements with noise reduction characteristics. In both cases, the evaluation of the acoustic performance allows a comparison of the design specifications with real performance data and its verification at the long run for an adequate validation of the adopted solutions. In this work the essential methods for an effective road noise management that allow the evaluation of road/tyre noise and of the acoustic performance of noise reduction devices, such as noise barriers. A method for the determination of the sound absorption in road pavements is also presented.Fundação para a Ciência e a Tecnologia (FCT

In situ assessment of the normal incidence sound absorption coefficient of asphalt mixtures with a new impedance tube

Normal incidence sound absorption coefficient of materials is usually calculated with the use of an impedance tube following the ISO 10534-2 international standard. The same is applied in the evaluation of the sound absorption characteristics of pavement mixtures. In this research an impedance tube which was specifically designed to be used in field conditions has been developed. In order test the tube six asphalt slabs were constructed in laboratory and its sound absorption coefficient measured with the new impedance tube. Then, several road sections, with different types of surface, among dense asphalt layers and thin layers, namely with rubberized asphalt were tested. In this paper, some considerations are made regarding the performance of the new impedance tube and the sound absorption coefficient of each asphalt mixtures.(undefined

Sound absorption coefficient of wet gap graded asphalt mixtures

Acoustic absorption properties of materials have often been used to reduce the generation and propagation of sound. The research carried out in this paper deals with sound absorption in relation to road surface layers. As the presence of water affects significantly the noise generated by the tyre-road contact, an evaluation of the sound absorption coefficient was made to several wet gap-graded mixtures with different levels of porosity and different contents of rubberized asphalt bitumen. A vacuum device was used to soak the interstices of the cores with water, which were then tested by means of an impedance tube, according with standard ISO 10534-2:1998. It was found that the values of the normal incidence sound absorption coefficient became smeared over the frequency spectrum in comparison with dry samples and that the quantity of rubber in the asphalt bitumen affected the way water fills the cores and, consequently, its sound absorption characteristics.(undefined

First report of Thielaviopsis paradoxa causing stem rot in Dracaena marginata in Brazil.

Comunicação

Cyber-Detective: a game for cyber crime prevention

Technologies are increasingly becoming a part of the daily lives of younger generations and with no supervised usage of these technologies, teenagers are exposed to various threats. To raise the awareness of teenagers in ages between 14 and 17 years old, and to provide a methodological tool for educational professionals working with the young and even for enforcement professionals investigating the cyber cases, an educational game about cyber security was designed and prototyped. A detective game was devised, where the player takes the role of a detective to investigate a cyber crime. To solve the case, the player must play several mini-games, where each one explores a specific thematic about cyber security. For example, in the prototype, the situation that the detective needs to solve is a ransomware case. The situations are introduced by a tridimensional animation, which appears as a cutscene introducing the game scene. It is an animation where one can see a teen trying to buy a pair of sneakers online and after downloading an application suggested in the website, his mobile phone is locked. Thus, he decides to search help from the police, where the detective will try to solve the problem. For that, the player has to solve several mini-games about sharing information in social networks, phishing and the importance of creating strong passwords. In these mini-games the player makes decisions and learns based on that, i.e., at the end of each mini-game each decision is explained to the player regardless of the choice being correct or incorrect. This way, the player is always informed of the various situations that can occur based on their behavior/decisions online. The prototype was developed for mobile devices and some preliminary tests were performed with teenagers. The tests showed that the teenagers improved their cyber security knowledge after playing the game. A cyber security educational game can be used as a tool for younger generations because it uses the technologies that are part of their daily lives and can contribute to the growing of their cyber security awareness. In the future, we hope to develop the full game, where other thematic will be included, namely, talking with strangers in social networks, dangers related with the webcam and microphone, online piracy and cyber bullying.info:eu-repo/semantics/publishedVersio